粤东长沙湾动力沉积地貌特征研究

Study on the characteristics of hydrodynamic, deposition and geomorphology in Changsha bay, Eastern Guangdong

  • 摘要: 本文根据水下地形、遥感影像以及水文观测等资料,综合运用遥感与地理信息系统(geographic information system, GIS)、表层沉积物分析等技术手段,研究了位于我国广东省东部沿海的海湾——长沙湾的动力沉积地貌特征。研究表明,长沙湾湾外水域涨、落潮流相对较弱,夏季,湾外以自西向东的沿岸流作用为主;冬季,以自东向西的沿岸流作用为主。湾口中东侧涨潮流占优,西侧落潮流占优,湾内涨落潮主流偏向东侧。湾内存在两处表层沉积物输运的汇聚区,分别位于上游黄江河出口右侧近岸和湾中部水域。口门段河道呈现滩淤槽冲的特征,右岸浅滩以及湾中部东侧水域淤积强度相对较大,湾口断面保持基本稳定,地形资料反映的海床淤积区与表层沉积物指示的床沙汇聚区吻合较好。湾顶存在由中段向东、西两侧的输沙过程,导致口门右岸浅滩不断淤积;湾中部是涨、落潮流优势发生转变的区域,泥沙容易落淤,是湾中部淤积的主要原因。上述两处水域发生淤积的原因与该区域表层沉积物指示的床沙输运路径基本一致。广东省东部沿海分布多个湾顶有中小河流入注的海湾,其口门段的动力沉积地貌过程与本研究区域具有一定的相似性。本研究的开展不仅对认识海湾复杂的动力结构及演变规律具有重要理论意义,而且对海湾的环境保护和开发治理具有一定的实际价值。

     

    Abstract: Based on the data of underwater topography, hydrology, and remote sensing images, this paper comprehensively uses remote sensing, geographic information system ,surface sediment analysis and other technical methods to analyze the characteristics of hydrodynamic, deposition and geomorphology in Changsha bay, which is located in the east coast of Guangdong Province, China. The results indicate that the tidal current outside the bay is relatively weak. The coastal current outside the bay is mainly from West to East in summer and from East to West in winter. The middle east of the bay mouth is dominated by flood current, while the west side is dominated by ebb current. The major flow inside the bay is biased towards the East. There are two convergence areas of surface sediment transport in the bay, one of which is located in the nearshore area on the right side of the outlet of Huangjing river, and the other is located in the middle of the bay. The outlet of the Huangjiang river is characterized by beach deposition and trough erosion. The siltation intensity of the shoals on the right bank of the estuary and the east of the middle of the bay is relatively large, and the section of the bay mouth remains basically stable. The seabed sediment convergence area indicated by the surface sediment is in good agreement with the seabed siltation area reflected by the topographic data. There is a sediment transport from the middle to the East and West sides at the top of the bay, which is the main reason for the continuous siltation of the shoal on the right bank of the outlet. The central part of the bay is the area where the predominance of tidal current changes, and the sediment is easy to fall and deposit, leading to continuous siltation in this part. The causes of siltation above are basically consistent with the transport path of bed sediment indicated by the surface sediment in these two zones. There are many bays in the east of Guangdong Province with medium or small rivers flowing into them, and the hydrodynamic, deposition and geomorphology process of the outlet is similar to the study area.This study not only has important theoretical significance for understanding the complex dynamic structure and evolution characteristics of the bay, but also has practical value for environmental protection and development and management of the bay.

     

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